plot_style.h

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/*
 * Copyright 2004 James Bursa <bursa@users.sourceforge.net>
 *
 * This file is part of NetSurf, http://www.netsurf-browser.org/
 *
 * NetSurf is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; version 2 of the License.
 *
 * NetSurf is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
/**
 * \file
 * plotter style interfaces, generic styles and style colour helpers.
 */
 
#ifndef NETSURF_PLOT_STYLE_H
#define NETSURF_PLOT_STYLE_H
 
#include <stdint.h>
#include <stdint.h>
#include <libwapcaplet/libwapcaplet.h>
#include "netsurf/types.h"
 
/** light grey widget base colour */
#define WIDGET_BASEC 0xd9d9d9
 
/** black blob colour */
#define WIDGET_BLOBC 0x000000
 
/** Transparent colour value. */
#define NS_TRANSPARENT 0x01000000
 
/** 22:10 fixed point */
#define PLOT_STYLE_RADIX (10)
 
/** Scaling factor for plot styles */
#define PLOT_STYLE_SCALE (1 << PLOT_STYLE_RADIX)
 
/* type for fixed point numbers */
typedef int32_t plot_style_fixed;
 
/* Convert an int to fixed point */
#define plot_style_int_to_fixed(v) ((v) << PLOT_STYLE_RADIX)
 
/* Convert fixed point to int */
#define plot_style_fixed_to_int(v) ((v) >> PLOT_STYLE_RADIX)
 
/* Convert fixed point to float */
#define plot_style_fixed_to_float(v) (((float)v) / PLOT_STYLE_SCALE)
 
/* Convert fixed point to double */
#define plot_style_fixed_to_double(v) (((double)v) / PLOT_STYLE_SCALE)
 
/**
 * Type of plot operation
 */
typedef enum {
        PLOT_OP_TYPE_NONE = 0, /**< No operation */
        PLOT_OP_TYPE_SOLID, /**< Solid colour */
        PLOT_OP_TYPE_DOT, /**< Dotted plot */
        PLOT_OP_TYPE_DASH, /**< Dashed plot */
} plot_operation_type_t;
 
 
/**
 * Plot style for stroke/fill plotters
 */
typedef struct plot_style_s {
        plot_operation_type_t stroke_type; /**< Stroke plot type */
        plot_style_fixed stroke_width; /**< Width of stroke, in pixels */
        colour stroke_colour; /**< Colour of stroke */
        plot_operation_type_t fill_type; /**< Fill plot type */
        colour fill_colour; /**< Colour of fill */
} plot_style_t;
 
 
/**
 * Generic font family type
 */
typedef enum {
        PLOT_FONT_FAMILY_SANS_SERIF = 0,
        PLOT_FONT_FAMILY_SERIF,
        PLOT_FONT_FAMILY_MONOSPACE,
        PLOT_FONT_FAMILY_CURSIVE,
        PLOT_FONT_FAMILY_FANTASY,
        PLOT_FONT_FAMILY_COUNT /**< Number of generic families */
} plot_font_generic_family_t;
 
 
/**
 * Font plot flags
 */
typedef enum {
        FONTF_NONE = 0,
        FONTF_ITALIC = 1,
        FONTF_OBLIQUE = 2,
        FONTF_SMALLCAPS = 4,
} plot_font_flags_t;
 
/**
 * Font style for plotting
 */
typedef struct plot_font_style {
        /**
         * Array of pointers to font families.
         *
         * May be NULL.  Array is NULL terminated.
         */
        lwc_string * const * families;
        plot_font_generic_family_t family; /**< Generic family to plot with */
        plot_style_fixed size; /**< Font size, in pt */
        int weight; /**< Font weight: value in range [100,900] as per CSS */
        plot_font_flags_t flags; /**< Font flags */
        colour background; /**< Background colour to blend to, if appropriate */
        colour foreground; /**< Colour of text */
} plot_font_style_t;
 
 
/* Darken a colour by taking seven eighths of each channel's intensity */
#define half_darken_colour(c1)                                          \
        ((((7 * (c1 & 0xff00ff)) >> 3) & 0xff00ff) |                    \
         (((7 * (c1 & 0x00ff00)) >> 3) & 0x00ff00))
 
/* Darken a colour by taking three quarters of each channel's intensity */
#define darken_colour(c1)                                               \
        ((((3 * (c1 & 0xff00ff)) >> 2) & 0xff00ff) |                    \
         (((3 * (c1 & 0x00ff00)) >> 2) & 0x00ff00))
 
/* Darken a colour by taking nine sixteenths of each channel's intensity */
#define double_darken_colour(c1)                                        \
        ((((9 * (c1 & 0xff00ff)) >> 4) & 0xff00ff) |                    \
         (((9 * (c1 & 0x00ff00)) >> 4) & 0x00ff00))
 
/* Lighten a colour by taking seven eighths of each channel's intensity
 * and adding a full one eighth intensity */
#define half_lighten_colour(c1)                                         \
        (((((7 * (c1 & 0xff00ff)) >> 3) + 0x200020) & 0xff00ff) |       \
         ((((7 * (c1 & 0x00ff00)) >> 3) + 0x002000) & 0x00ff00))
 
/* Lighten a colour by taking 12/16ths of each channel's intensity
 * and adding a full 4/16ths intensity */
#define lighten_colour(c1)                                              \
        (((((3 * (c1 & 0xff00ff)) >> 2) + 0x400040) & 0xff00ff) |       \
         ((((3 * (c1 & 0x00ff00)) >> 2) + 0x004000) & 0x00ff00))
 
/* Lighten a colour by taking 9/16ths of each channel's intensity
 * and adding a full 7/16ths intensity */
#define double_lighten_colour(c1)                                       \
        (((((9 * (c1 & 0xff00ff)) >> 4) + 0x700070) & 0xff00ff) |       \
         ((((9 * (c1 & 0x00ff00)) >> 4) + 0x007000) & 0x00ff00))
 
/* Blend two colours by taking half the intensity of each channel in the first
 * colour and adding them to half the intensity of each channel in the second
 * colour */
#define blend_colour(c0, c1)                                            \
        (((((c0 & 0xff00ff) + (c1 & 0xff00ff)) >> 1) & 0xff00ff) |      \
         ((((c0 & 0x00ff00) + (c1 & 0x00ff00)) >> 1) & 0x00ff00))
 
/**
 * Obtain the luminance of a colour according to ITU BT.601
 *
 * ITU BT.601 formula is
 * Y = 0.299 R + 0.587 G + 0.114 B
 * actual values are
 * Y = 76/255 R + 150/255 G + 29/255 B
 * Y = 0.298 R + 0.588 G + 0.113 B
 *
 * @note if additional performance is required this could be altered to
 *       Y = 0.375 R + 0.5 G + 0.125 B
 *       with
 *       Y = (R << 1 + R + G << 2 + B) >> 3
 */
#define colour_lightness(c0)                                            \
        ((((c0 & 0x0000ff) *  77) >>  8) +                              \
         (((c0 & 0x00ff00) * 151) >> 16) +                              \
         (((c0 & 0xff0000) *  30) >> 24))
 
/* Choose either black or white, depending on which is nearest to the
 * percieved lightness of the supplied colour, c0. */
#define colour_to_bw_nearest(c0)                                        \
        ((colour_lightness(c0) > (0xff / 2)) ? 0xffffff : 0x000000)
 
/* Choose either black or white, depending on which is furthest from the
 * percieved lightness of the supplied colour, c0. */
#define colour_to_bw_furthest(c0)                                       \
        ((colour_lightness(c0) > (0xff / 2)) ? 0x000000 : 0xffffff)
 
/* Mix two colours according to the proportion given by p, where 0 <= p <= 255
 * p = 0 gives result ==> c1,  p = 255 gives result ==> c0 */
#define mix_colour(c0, c1, p)                                           \
        ((((((c1 & 0xff00ff) * (255 - p)) +                             \
            ((c0 & 0xff00ff) * (      p))   ) >> 8) & 0xff00ff) |       \
         (((((c1 & 0x00ff00) * (255 - p)) +                             \
            ((c0 & 0x00ff00) * (      p))   ) >> 8) & 0x00ff00))
 
/* Get the red channel from a colour */
#define red_from_colour(c)                                              \
        ((c      ) & 0xff)
 
/* Get the green channel from a colour */
#define green_from_colour(c)                                            \
        ((c >>  8) & 0xff)
 
/* Get the blue channel from a colour */
#define blue_from_colour(c)                                             \
        ((c >> 16) & 0xff)
 
/* Swap red and blue channels in a colour */
#define colour_rb_swap(c)                                               \
        (((0x000000ff & c) << 16) |                                     \
         ((0x0000ff00 & c)      ) |                                     \
         ((0x00ff0000 & c) >> 16))
 
/** Colour components */
enum plot_colour_component {
        PLOT_COLOUR_COMPONENT_RED,
        PLOT_COLOUR_COMPONENT_GREEN,
        PLOT_COLOUR_COMPONENT_BLUE,
        PLOT_COLOUR_COMPONENT_ALPHA,
};
 
/**
 * Engorge a particular colour channel.
 *
 * \param[in] col   The colour to engorge a component of.
 * \param[in] dark  Whether col is a dark colour.
 * \param[in] comp  Colour component to engorge.
 */
static inline colour colour_engorge_component(
                colour col,
                bool dark,
                enum plot_colour_component comp)
{
        static const colour msk[PLOT_COLOUR_COMPONENT_ALPHA] = {
                [PLOT_COLOUR_COMPONENT_RED]   = 0x0000ff,
                [PLOT_COLOUR_COMPONENT_GREEN] = 0x00ff00,
                [PLOT_COLOUR_COMPONENT_BLUE]  = 0xff0000,
        };
        colour d = dark ? darken_colour(col) : double_darken_colour(col);
        colour l = dark ? double_lighten_colour(col) : lighten_colour(col);
 
        assert(comp < PLOT_COLOUR_COMPONENT_ALPHA);
 
        return (msk[comp] & l) | (~msk[comp] & d);
}
 
 
/* global fill styles */
extern plot_style_t *plot_style_fill_white;
extern plot_style_t *plot_style_fill_red;
extern plot_style_t *plot_style_fill_black;
 
 
/* Box model debug outline styles for content, padding and margin edges */
extern plot_style_t const * const plot_style_content_edge;
extern plot_style_t const * const plot_style_padding_edge;
extern plot_style_t const * const plot_style_margin_edge;
 
 
/* Broken object replacement styles */
extern plot_style_t const * const plot_style_broken_object;
extern plot_font_style_t const * const plot_fstyle_broken_object;
 
 
/* other styles */
extern plot_style_t *plot_style_caret;
extern plot_style_t *plot_style_fill_wbasec;
extern plot_style_t *plot_style_fill_darkwbasec;
extern plot_style_t *plot_style_fill_lightwbasec;
extern plot_style_t *plot_style_fill_wblobc;
extern plot_style_t *plot_style_stroke_wblobc;
extern plot_style_t *plot_style_stroke_darkwbasec;
extern plot_style_t *plot_style_stroke_lightwbasec;
 
 
/* Default font style */
extern plot_font_style_t const * const plot_style_font;
 
 
#endif